High efficiency low actuation force inlet door

ABSTRACT

An inlet system for an inlet in a flow field includes an inlet recess housing having an interior with forward and rear end walls, a base wall, and an opening formed in an upper surface thereof. An intake duct is formed in a rear end wall of the inlet recess. An inlet door has a first end pivotally connected to a forward wall and a trailing edge directed to the rear end wall of the inlet housing such that the inlet door selectively closes the opening of the inlet housing. An overlap member can extend from the rear end wall of the inlet recess to a predetermined distance adjacent a trailing edge of the door. A deflector is provided having an end deflecting portion in contact with the trailing edge of the door over at least a portion of the inlet door&#39;s pivoting path. Side deflecting portions project from the end deflecting portion toward the front wall of the inlet housing. The deflector controls pressure recovery of flow field at a fully open position of the door until the trailing edge of the door clears the end deflecting portion of the deflector.

STATEMENT OF GOVERNMENT INTEREST

The invention described herein may be manufactured and used by or forthe Government of the United States of America for governmental purposeswithout the payment of any royalties thereon or therefor.

BACKGROUND OF THE INVENTION

(1) Field of the Invention

This invention generally relates to an intake door system thatefficiently recovers the dynamic pressure in an external flow around amoving vehicle and does not suffer from opening resistance forcesgenerated through pressure recovery in the inlet recess.

(2) Description of the Prior Art

In the current art for submarine torpedo launch systems designs (asgenerally shown in FIG. 1), a high efficiency inlet 100 is included atan intake side of the system. This inlet 100 includes a recess 102, anintake duct 104 and a hinged door 106. The door 106 is designed so thatwhen it is opened, the dynamic pressure of the mean flow is channeleddirectly into the intake duct 104. This pressure is intended to assist aturbine pump 118 in launching a torpedo 116 from a torpedo tube 108.

The basic operation of the type of launch system shown in FIG. 1 is asfollows. The inlet door 106, a slide valve 110, and a shutterway recess112 are opened to create an open flow path through the launch system.Prior to launch, the pressure in the inlet recess 102 and the pressurein the shutterway recess 112 each independently increase to somefraction of the available dynamic head, as a result of forward motion ofthe platform. Any imbalance in the pressure in these two recesses 102,112 causes fluid in the launch system, and any device, such as torpedo116, in the torpedo tube 108, to begin to move. When launch isinitiated, the turbine pump 118 begins to rotate and fluid is drawnthrough the inlet door 106, the inlet recess 102, and the intake duct104 and into the turbine pump 118. The turbine pump 118 forces fluidinto an impulse tank 114 housing the slide valve 110, through the slidevalve 110, down the torpedo tube 108 and thereby carrying the weapon 116in the torpedo tube 108 through the shutterway recess 112 and out of theplatform.

In practical systems, the inlet door 106, when fully open, does noteffectively direct the external dynamic pressure into the intake duct104. A second problem is that when the inlet door 106 just begins toopen, the dynamic pressure is effectively channeled into the inletrecess 102. This pressurizes a back or rear side of the inlet door 106,preventing it from fully opening. FIG. 2 shows further detail of thisknown type of inlet 100 and illustrates the basic back-pressure problemwith arrows 120.

The following patents, for example, disclose various inlet systems andarrangements:

-   -   U.S. Pat. No. 4,378,097 to Ferguson et al.;    -   U.S. Pat. No. 4,620,679 to Karanian;    -   U.S. Pat. No. 5,033,693 to Livingston et al.;    -   U.S. Pat. No. 5,078,341 to Bichler et al.;    -   U.S. Pat. No. 5,088,660 to Karanian;    -   U.S. Pat. No. 5,116,251 to Bichler et al.; and    -   U.S. Pat. No. 6,264,137 to Sheoran.

Specifically, Ferguson et al. disclose a smooth surfaced, submerged airinlet for use generally forwardly of an engine in an aircraft (missileor other air vehicle). The inlet has an opening having wall surfacesadapted to be flush with or inwardly of an aircraft body surface. Thewall surfaces of the opening have a leading and outer end in a plane andthe surfaces extend inwardly to form an uncovered shallow channel-shapedportion to the inlet, the channel portion deepening inwardly in thetrailing direction and continuing into a partial ellipse portion of theopening. The ellipse portion deepens inwardly as it extends in atrailing direction and has substantially parallel wall surfacesextending outwardly of the ellipse in the direction toward the level ofthe plane. There are extensions of said substantially parallel wallsurfaces diverging outwardly to said plane. There is an inwardlytrailing surface, spaced outwardly from the partial ellipse portion,being joined to the substantially parallel wall surfaces to form anouter cover for a trailing part of said inlet and of said partialellipse portion. The inlet, including the cover, trails inwardly and iscontoured radially as it trails to form a substantially circular wallsurface at its inner end.

The patent to Karanian '679 discloses a two-dimensional inlet for a highspeed ram jet missile and includes in combination an educated slot and asingle ramp for varying the geometry of the inlet.

Livingston et al. discloses an inlet having a single-piece, flexibleinlet ramp skin. A corrugated member is rigidly coupled to the interiorsurface of the ramp skin to hold the skin rigid in one direction butpermit it to be extremely flexible in a second direction. A plurality ofbeams extends perpendicular to the ridges and grooves of the corrugatedmember to hold the skin in position in the second direction. Mechanicalactuators are coupled to the beams for applying force to vary the shapeof the beams and thus the shape of the ramp skin. The inlet area isvaried as the ramp skin is moved. The beam member and ramp skin areelastically deformable from an intermediate position in a firstdirection to increase the area of the inlet and in a second direction todecrease the area of the inlet. Shaping the beam and ramp skin to be atan intermediate position when not deformed permits a greater range ofmovement and a more variable inlet area for a given material and weight.

Bichler et al. '341 disclose a hydraulically-pivotable inlet ramp with abox-like shaped cross-section for supplying air into engines ofsupersonic or hypersonic airplanes. The inlet ramp, comprised of aplurality of relatively movable elements, can be adjusted into a numberof different positions to optimize air flow under various machconditions, as well as control a boundary air layer inlet.

The patent to Karanian '660 discloses a supersonic inlet flow ductprovided with a pivoting bleed stability door and biasing spring. Thedoor opens under the influence of increased static fluid pressure behinda shock front, which is displaced forwardly by a downstream pressureperturbation. The opened door diverts portions of the inlet duct flowstabilizing the shock front and downstream shock train within the ductuntil the perturbation subsides.

Bichler et al. '251 disclose an inlet system, which can be used for allsupersonic or hypersonic engine inlets and comprises two or severalseparate parallel ducts, which must be switched over in specific phasesof flight. This is accomplished with a duct shaped parallel inletelement pivotably assigned to the inlet ramp of the inlet, which as achannel-connecting re-direction member alternately can close off theturbo-jet inlet duct as well as also the ramjet inlet. Preferably, theconstruction comprises a plurality of pivotably connected box-likeelements interconnected in a movable manner.

The patent to Sheoran discloses an air inlet assembly for bringing airto an auxiliary power unit mounted in the compartment of an aircraft.The assembly includes a duct extending from an intake contoured toconform to the aircraft fuselage to an exit coupled to the inlet plenumof the auxiliary power unit. A first door hingeably mounted to the aftside of said intake and moveable from an open position to a closedposition where said first door lies flush against intake, said firstdoor having a closing wall and two side walls and a second doorhingeably mounted to the forward end of said intake, said second doorhaving a plate with two inwardly extending walls, each of said inwardlyextending walls hinged to one of said side walls so that the second doorrotates with said first door. During ground operation, air that wouldhave swirled around the side walls of the first door thus generatinginlet corner vortices are now blocked by the side walls of the seconddoor.

It should be understood that the present invention would in fact enhancethe functionality of the above patents by providing a high efficiencyinlet that can be easily opened under dynamic conditions.

SUMMARY OF THE INVENTION

Therefore it is an object of this invention to provide a high efficiencyinlet door.

Another object of this invention is to provide a high efficiency inletdoor having a low actuation force.

Still another object of this invention is to provide a high efficiency,low actuation force inlet door that does not adversely affecthydrodynamic flow about the inlet door.

Yet another object of this invention is to control pressure recovery onthe inlet door when the inlet door is fully open and reduce backpressure on the inlet door during an initial stage of opening the inletdoor.

In accordance with one aspect of this invention, there is provided aninlet system for fluid flow around a moving vehicle includes an inletrecess housing having a substantially vacant interior with forward andrear end walls, a base wall, and an opening formed in an upper surfacethereof. An intake duct is formed in a rear end wall of the inletrecess. An inlet door has a first end pivotally connected to a forwardwall and a trailing edge directed to the rear end wall of the inletrecess such that the inlet door selectively closes the opening of theinlet recess. An overlap member extends from at least the rear end wallof the inlet recess to a predetermined overlap adjacent a trailing edgeof the door. A deflector is provided having an end deflecting portion incontact with the trailing edge of the door over a predetermined arcuatedistance and side deflecting portions projecting from the end deflectingportion toward the front wall of the inlet recess. The deflectorarrangement controls pressure recovery of fluid at a fully open positionof the door and controls a pressure on a recess side of the door untilthe trailing edge of the door clears the end deflecting portion of thedeflector in a fluid flow direction from the inlet door to the intakeduct.

BRIEF DESCRIPTION OF THE DRAWINGS

The appended claims particularly point out and distinctly claim thesubject matter of this invention. The various objects, advantages andnovel features of this invention will be more fully apparent from areading of the following detailed description in conjunction with theaccompanying drawings in which like reference numerals refer to likeparts, and in which:

FIG. 1 is a schematic diagram of a prior art ejection system;

FIG. 2 is a side schematic view of a prior art high efficiency inlet foruse in the system of FIG. 1;

FIGS. 3A, 3B, and 3C are side schematic views of a high efficiency inletsystem at varying stages of operation according to a preferredembodiment of the present invention; and

FIG. 4 is a detail perspective view of a portion of the system shown inFIGS. 3A, 3B and 3C.

DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring to FIGS. 3A, 3B and 3C, the features of an inlet system 10 areshown at three stages of operation. The inlet system includes severalprimary components including an inlet recess 12 of a substantiallyrectangular shape and built into the ship hull (not shown in FIG. 3).This enclosure serves as a housing for all mechanisms and allows anintake door 14 to open and close without interference from other hullsystems. The inlet recess 12 is nominally isolated from other shipcompartments, thereby preventing fluid from flowing through the inletrecess 12 and into other compartments. Flow is constrained to flowthrough the inlet recess and into an intake duct 16.

The inlet door 14 is essentially a trap door mounted by at least onehinge member 18 at a leading edge 14 a of the door 14. A longitudinalaxis of the inlet door 14 is aligned with a mean flow direction of anexternal flow over the vessel hull. The inlet door 14 is opened usinglarge hydraulic systems (not shown) connected to a side 14 d of inletdoor 14 facing the inlet recess 12. Any linear actuator having thenecessary opening and closing force can be used to open the door.

Fluid is drawn from the inlet recess 12 to a turbine pump (see FIG. 1)through the intake duct 16. An entrance to the intake duct 16 faces thatpart of the inlet recess 12 adjacent an inlet door opening 20 shown inFIGS. 3B and 3C. Minimal flow restrictions exist between the intake duct16 and the door opening 20.

An overlap 22 is provided which covers or overlays a portion of theinlet door 14 adjacent a trailing edges 14 b thereof. This overlap 22helps form a high pressure cavity on the top surface 14 c of the intakedoor 14 as it begins to open.

An intake fence 24 is placed at the trailing edge 14 b of the intakedoor 14. A sliding seal is provided between the trailing edge 14 b ofthe intake door 14 and the intake fence 24. The intake fence 24 andresultant seal prevent flow and pressure communication between an areaabove the inlet door 14 and the inlet recess 12 during initial openingof the inlet door 14. A detail view of the intake fence 24 and sideshields 26 is provided as FIG. 4. In FIG. 4, one side shield 26 is notshown.

Side shields 26 are provided to prevent flow and pressure communicationbetween the area over the intake door 14 and the inlet recess 12 as door14 begins to open. The side shields 26 extend from opposing edges of theintake fence 24 and below a planar surface of the overlap 22 so as tophysically fit within the inlet recess 12. A sliding seal between outeredges of the inlet door 14 and the side shields 26 is needed to preventflow around the edges of the inlet door 14.

The combination of the overlap 22, intake fence 24, and side shields 26integrate to improve pressure recovery performance, and preventexcessive back pressure from interfering with opening of the intake door14. As the intake door 14 begins to open (FIG. 3B), a high velocity flowis directed between the overlap 22 and the top surface 14 c of the inletdoor 14. The cavity formed between the top surface 14 c of intake door14, side shields 26, and intake fence 24 is pressurized with therecovered dynamic pressure. As a result, there is a large opening forceon the intake door 14. Because sealing of the side shields 26 and theintake fence 24 are not perfect with the perimeter of the inlet door 14,some flow is forced into the intake recess 12. A predetermined amount offlow is allowed to escape through the hinges 18 and gaps in the sideshields 26 upstream of the overlap 22 (outside of the pressurized cavityformed above the inlet door 14). This predetermined flow allows somepressurization of the intake recess 12. Without this flow, the inletdoor 14 would have to be forced shut to overcome the pressure forcesabove the inlet door 14.

This flow control arrangement is maintained until the inlet door 14opens sufficiently far for the pressure recovery effectiveness of thedoor to drop substantially (from nearly 100% at a few degrees open angleto approximately 30% at 15 degrees open angle). When the trailing edge14 b of the inlet door 14 passes the bottom of the intake fence 24, thecavity above the inlet door 14 comes into immediate communication withthe inlet recess 12. A sudden rise in pressure of the inlet recess 12increases back-pressure on the inside 14 d of the inlet door 14. Theintake fence 24 and side shields 26 are designed so that when thiscommunication occurs, the resulting forces on the inlet door 14 are wellwithin the opening actuation force of the hydraulic system for the inletdoor 14.

As shown in FIG. 3C, the inlet door 14 continues to open until thetrailing edge 14 b of the inlet door 14 and the bottom of the intakefence 24 entirely expose the intake duct 16.

The presence of the overlap 22 has a secondary function of improving thepressure recovery of the inlet recess 12. A sharp outer edge 22 a of theoverlap 22 tends to direct high velocity external flow into the recess12 and intake duct 16. The inlet door 14 herein eliminates any backpressurization that can prevent opening of the inlet door 14 andimproves the pressure recovery performance of the entire inlet system10. The combined effect of the intake fence 24, side shields 26, andoverlap 22 is to create a pressurized cavity above the intake door 14during the initial opening of the door and thereby compensates for thepressurization of the recess 12.

It will be understood that the arrangement presented herein can bemodified in many ways in order to achieve the desired result. Examplesof alternate configurations include retractable side shields and fencesthat can be removed when the door is fully open; and controlling the gapbetween the fence and the door to adjust a force on the door. It is alsopossible to eliminate the need for high power hydraulics by restrictingthe flow with sufficient control to adjust the relative pressure aboveand below the intake door. The elimination of high-powered hydraulicscan significantly reduce the cost of the intake door system.

In view of the above detailed description, it is anticipated that theinvention herein will have far reaching applications other than thosedescribed.

This invention has been disclosed in terms of certain embodiments. Itwill be apparent that many modifications can be made to the disclosedapparatus without departing from the invention. Therefore, it is theintent of the appended claims to cover all such variations andmodifications as come within the true spirit and scope of thisinvention.

1. An inlet system for fluid flow comprising: an inlet housing having aforward wall, a rear end wall, a base wall, and an opening formed in anupper surface thereof; an intake duct formed in said rear end wall ofsaid inlet housing; an inlet door having a first edge pivotallyconnected to a forward wall of said inlet housing and a trailing edgedirected to the rear end wall of said inlet housing, said inlet doorbeing capable of selectively closing the inlet housing opening; an enddeflecting portion positioned in said inlet housing and sealable againstthe trailing edge of said inlet door over at least a portion of theinlet door's pivoting path; and side deflecting portions positioned insaid inlet housing and sealable against said inlet door wherein saidside deflecting portions are substantially triangular with a base of thetriangle mounted to the end deflecting portion and an apex of thetriangle terminating a distance away from the end deflecting portion. 2.The system according to claim 1 further comprising hinges, pivotallyconnecting said inlet housing to said inlet door.
 3. The systemaccording to claim 1 further comprising an overlap formed as part ofsaid inlet housing and extending into said inlet housing opening fromsaid rear end wall, said overlap preventing outward opening of saidinlet door.
 4. The system according to claim 1 wherein the said enddeflecting portion transverses an entire width of said inlet recesshousing.
 5. An inlet system for fluid flow comprising: an inlet housinghaving a forward wall, a rear end wall, a base wall, and an openingformed in an upper surface thereof; an intake duct formed in said rearend wall of said inlet housing; an inlet door having a first edgepivotally connected to a forward wall of said inlet housing and atrailing edge directed to the rear end wall of said inlet housing, saidinlet door being capable of selectively closing the inlet housingopening; an end deflecting portion positioned in said inlet housing andsealable against the trailing edge of said inlet door over at least aportion of the inlet door's pivoting path, wherein said end deflectingportion is positioned within said inlet recess housing and above saidintake duct.
 6. The system according to claim 5 wherein said enddeflecting portion includes an arcuate face corresponding to an arcuatepath of the trailing edge of said inlet door over a predetermineddistance.
 7. An inlet system for fluid flow comprising: an inlet housinghaving a forward wall, a rear end wall, a base wall, and an openingformed in an upper surface thereof; an intake duct formed in said rearend wall of said inlet housing; an inlet door having a first edgepivotally connected to a forward wall of said inlet housing and atrailing edge directed to the rear end wall of said inlet housing, saidinlet door being capable of selectively closing the inlet housingopening; an end deflecting portion positioned in said inlet housing andsealable against the trailing edge of said inlet door over at least aportion of the inlet door's pivoting path, wherein said end deflectingportion includes an arcuate face corresponding to an arcuate path of thetrailing edge of said inlet door over a predetermined distance.